Apparatus for downward displacement of an inner tube within a coring barrel

Abstract

Downward displacement of an inner tube with respect to the outer tube in a coring tool is effectuated by an apparatus comprising a bearing assembly, a cylinder, a piston telescopically disposed within the cylinder, and a mechanism for selectively applying an hydraulic force to the piston. The bearing assembly is longitudinally fixed with respect to the outer tube while providing rotational freedom with respect to the outer tube. A cylinder is axially disposed within the coring tool, is connected to the bearing assembly, and hence is rotationally free with respect to the outer tube. The piston, which is telescopically disposed within a cylinder, is downwardly longitudinally displaceable within the cylinder, and hence with respect to the outer tube. A mechanism is incorporated within the coring tool for selectively applying a hydraulic force to the piston in order to longitudinally displace the piston downwardly within the cylinder. The inner tube, being coupled to the piston, is thus downwardly displaced within the coring tool.

We claim: 
     
       1. An apparatus for providing downward longitudinal displacement in an inner tube with respect to an outer tube in a coring tool comprising: a cylinder longitudinally fixed with respect to said outer tube, said cylinder having a bypass port defined therethrough and a plurality of conduits defined through said cylinder communicating with the interior of said outer tube to provide a flow path independent of said bypass port through said cylinder, said bypass port having substantially less flow resistance than said plurality of conduits and therefore preferentially diverting hydraulic fluid from said interior of said outer tube above said cylinder to an annular spaced defined between said cylinder and said outer tube;   a primary piston telescopically disposed within said cylinder and forming a sealed and slideable relationship therewith, said piston connected to said inner tube; and   means for selectively closing said bypass port defined in said cylinder to thereby force said hydraulic fluid to flow through said ducts to said interior of said cylinder against said piston in sealed telescopic relationship with said cylinder,   whereby said hydraulic force is applied to said cylinder, and said cylinder is longitudinally displaced downwardly with respect to said outer tube.   
     
     
       2. An apparatus in a coring tool for effecting a relative downward, longitudinal displacement of an inner barrel within said coring tool with respect to an outer tube of said coring tool comprising: a bearing assembly longitudinally fixed with respect to said outer tube and rotationally free with respect thereto;   a cylinder axially disposed within said coring tool and connected to said bearing assembly, said cylinder rotationally free with respect to said outer tube;   a piston telescopically disposed within said cylinder and downwardly longitudinally displaceable with respect thereto;   means for selectively applying a hydraulic force to said piston to longitudinally displace said piston with respect to said cylinder, said inner tube being coupled to said piston,   wherein said means for selectively applying said hydraulic force to said piston comprises an integral upper extension of said cylinder connected to said bearing assembly, said upper section of said cylinder defining a bypass port therethrough to divert hydraulic fluid from inside said outer tube away from said piston, a drop ball selectively disposable within said coring tool sized and configured to seal said bypass port, a plurality of ducts defined in said upper section of said cylinder and communicating the interior of said outer tube with the interior of said cylinder and with said piston,   whereby hydraulic force is applied to said piston, and whereby said inner tube is selectively longitudinally displaced within said coring tool with respect to said outer tube.   
     
     
       3. An apparatus for effecting downward longitudinal displacement of an inner tube with respect to an outer tube in a coring tool comprising: a bearing assembly longitudinally fixed with respect to said outer tube and rotationally free therefrom;   a bearing retainer bottom end connected to said bearing assembly, said retainer bottom end having a bypass port defined therethrough, and a cylindrical lower termination, a plurality of ducts defined through said bottom end between said cylinder and the interior of said outer tube to provide a flow path independent of said bypass port, said bypass port having less flow resistance than said ducts and therefore preferentially diverting hydraulic fluid from said interior of said outer tube above said retainer bottom end to an annular space defined between said cylinder and said outer tube;   a primary piston telescopically disposed within said cylinder and forming a sealed and slidable relationship therewith, said piston connected to said inner tube; and   means for selectively closing said bypass port defined in said retainer bottom end to thereby force said hydraulic fluid to flow through said ducts to said interior of said cylinder against said piston in sealed telescopic relationship with said cylinder,   whereby said hydraulic force is applied to said piston, and said piston is longitudinally displaced with respect to said outer tube.   
     
     
       4. The apparatus of claim 3 further comprising means for selectively locking said piston with respect to said cylinder. 
     
     
       5. The apparatus of claim 4, wherein said means for selectively locking said piston with respect to said cylinder comprises a shear pin disposed at least in part through said piston and adjacent cylinder. 
     
     
       6. The apparatus of claim 4, wherein said means for locking said primary piston with respect to said cylinder comprises an inner mandrel axially extending from said retainer bottom end, a locking dog disposed at least in part within said inner mandrel and radially displaceable within said inner mandrel, said locking dog engageable with said primary piston, and an inner piston telescopically and axially disposed within said inner mandrel, said inner piston biased to assume a first position in contact with said locking dog to urge said locking dog into engagement with said primary piston, thereby locking said primary piston with respect to said cylinder, said plurality of ducts defined in said retainer bottom end communicating with a bore defined in said inner mandrel, said inner piston telescopically disposed within said bore so that hydraulic fluid and force is supplied through said ducts to said inner piston, said inner piston responsively assuming a second position with respect to said locking dog to permit said locking dog to move radially inward out of engagement with said primary piston, thereby selectively freeing said primary piston with respect to said cylinder.